var Utils     = require("../../utils")
  , DataTypes = require("../../data-types")
  , util      = require("util")

module.exports = (function() {
  var QueryGenerator = {
    dialect: 'mysql',
    addSchema: function(opts) {
      var tableName
      var schema        = (!!opts && !!opts.options && !!opts.options.schema ? opts.options.schema : undefined)
      var schemaDelimiter  = (!!opts && !!opts.options && !!opts.options.schemaDelimiter ? opts.options.schemaDelimiter : undefined)

      if (!!opts && !!opts.tableName) {
        tableName = opts.tableName
      }
      else if (typeof opts === "string") {
        tableName = opts
      }

      if (!schema || schema.toString().trim() === "") {
        return tableName
      }

      return this.quoteIdentifier(schema + (!schemaDelimiter ? '.' : schemaDelimiter) + tableName, false)
    },

    createSchema: function() {
      var query = "SHOW TABLES"
      return Utils._.template(query)({})
    },

    dropSchema: function(tableName, options) {
      return QueryGenerator.dropTableQuery(tableName, options)
    },

    showSchemasQuery: function() {
      return "SHOW TABLES"
    },

    createTableQuery: function(tableName, attributes, options) {
      options = Utils._.extend({
        engine: 'InnoDB',
        charset: null
      }, options || {})

      var query   = "CREATE TABLE IF NOT EXISTS <%= table %> (<%= attributes%>)<%= comment %> ENGINE=<%= engine %> <%= charset %> <%= collation %>"
        , primaryKeys = []
        , foreignKeys = {}
        , attrStr = []

      for (var attr in attributes) {
        if (attributes.hasOwnProperty(attr)) {
          var dataType = this.mysqlDataTypeMapping(tableName, attr, attributes[attr])

          if (Utils._.includes(dataType, 'PRIMARY KEY')) {
            primaryKeys.push(attr)
            dataType = dataType.replace(/PRIMARY KEY/, '');
          }

          if (Utils._.includes(dataType, 'REFERENCES')) {
            // MySQL doesn't support inline REFERENCES declarations: move to the end
            var m = dataType.match(/^(.+) (REFERENCES.*)$/)
            dataType = m[1];
            foreignKeys[attr] = m[2]
          }

          attrStr.push(this.quoteIdentifier(attr) + " " + dataType)
        }
      }

      var values = {
        table: this.quoteIdentifier(tableName),
        attributes: attrStr.join(", "),
        comment: options.comment && Utils._.isString(options.comment) ? " COMMENT " + this.escape(options.comment) : "",
        engine: options.engine,
        charset: (options.charset ? "DEFAULT CHARSET=" + options.charset : ""),
        collation: (options.collate ? "COLLATE " + options.collate : "")
      }
      , pkString = primaryKeys.map(function(pk) { return this.quoteIdentifier(pk) }.bind(this)).join(", ")

      if (!!options.uniqueKeys) {
        Utils._.each(options.uniqueKeys, function(columns) {
          values.attributes += ", UNIQUE uniq_" + tableName + '_' + columns.fields.join('_') + " (" + columns.fields.join(', ') + ")"
        })
      }

      if (pkString.length > 0) {
        values.attributes += ", PRIMARY KEY (" + pkString + ")"
      }

      for (var fkey in foreignKeys) {
        if(foreignKeys.hasOwnProperty(fkey)) {
          values.attributes += ", FOREIGN KEY (" + this.quoteIdentifier(fkey) + ") " + foreignKeys[fkey]
        }
      }

      return Utils._.template(query)(values).trim() + ";"
    },

    dropTableQuery: function(tableName, options) {
      options = options || {}

      var query = "DROP TABLE IF EXISTS <%= table %>;"

      return Utils._.template(query)({
        table: this.quoteIdentifier(tableName)
      })
    },

    showTablesQuery: function() {
      return 'SHOW TABLES;'
    },

    uniqueConstraintMapping: {
      code: 'ER_DUP_ENTRY',
      map: function(str) {
        // we're manually remvoving uniq_ here for a future capability of defining column names explicitly
        var match = str.replace('uniq_', '').match(/Duplicate entry .* for key '(.*?)'$/)
        if (match === null || match.length < 2) {
          return false
        }

        return match[1].split('_')
      }
    },

    addColumnQuery: function(tableName, attributes) {
      var query      = "ALTER TABLE `<%= tableName %>` ADD <%= attributes %>;"
        , attrString = []

      for (var attrName in attributes) {
        var definition = attributes[attrName]

        attrString.push(Utils._.template('`<%= attrName %>` <%= definition %>')({
          attrName: attrName,
          definition: this.mysqlDataTypeMapping(tableName, attrName, definition)
        }))
      }

      return Utils._.template(query)({ tableName: tableName, attributes: attrString.join(', ') })
    },

    removeColumnQuery: function(tableName, attributeName) {
      var query = "ALTER TABLE `<%= tableName %>` DROP `<%= attributeName %>`;"
      return Utils._.template(query)({ tableName: tableName, attributeName: attributeName })
    },

    changeColumnQuery: function(tableName, attributes) {
      var query      = "ALTER TABLE `<%= tableName %>` CHANGE <%= attributes %>;"
      var attrString = []

      for (var attrName in attributes) {
        var definition = attributes[attrName]

        attrString.push(Utils._.template('`<%= attrName %>` `<%= attrName %>` <%= definition %>')({
          attrName: attrName,
          definition: definition
        }))
      }

      return Utils._.template(query)({ tableName: tableName, attributes: attrString.join(', ') })
    },

    renameColumnQuery: function(tableName, attrBefore, attributes) {
      var query      = "ALTER TABLE `<%= tableName %>` CHANGE <%= attributes %>;"
      var attrString = []

      for (var attrName in attributes) {
        var definition = attributes[attrName]

        attrString.push(Utils._.template('`<%= before %>` `<%= after %>` <%= definition %>')({
          before: attrBefore,
          after: attrName,
          definition: definition
        }))
      }

      return Utils._.template(query)({ tableName: tableName, attributes: attrString.join(', ') })
    },

    bulkInsertQuery: function(tableName, attrValueHashes, options) {
      var query = "INSERT<%= ignoreDuplicates %> INTO <%= table %> (<%= attributes %>) VALUES <%= tuples %>;"
        , tuples = []
        , allAttributes = []

      Utils._.forEach(attrValueHashes, function(attrValueHash, i) {
        Utils._.forOwn(attrValueHash, function(value, key, hash) {
          if (allAttributes.indexOf(key) === -1) allAttributes.push(key)
        })
      })

      Utils._.forEach(attrValueHashes, function(attrValueHash, i) {
        tuples.push("(" +
          allAttributes.map(function (key) {
            return this.escape(attrValueHash[key])
          }.bind(this)).join(",") +
        ")")
      }.bind(this))

      var replacements  = {
        ignoreDuplicates: options && options.ignoreDuplicates ? ' IGNORE' : '',
        table: this.quoteIdentifier(tableName),
        attributes: allAttributes.map(function(attr){
                      return this.quoteIdentifier(attr)
                    }.bind(this)).join(","),
        tuples: tuples
      }

      return Utils._.template(query)(replacements)
    },

    deleteQuery: function(tableName, where, options) {
      options = options || {}

      var table = this.quoteIdentifier(tableName)
      if (options.truncate === true) {
        // Truncate does not allow LIMIT and WHERE
        return "TRUNCATE " + table
      }

      where = this.getWhereConditions(where)
      var limit = ""

      if(Utils._.isUndefined(options.limit)) {
        options.limit = 1;
      }

      if(!!options.limit) {
        limit = " LIMIT " + this.escape(options.limit)
      }

      return "DELETE FROM " + table + " WHERE " + where + limit
    },

    bulkDeleteQuery: function(tableName, where, options) {
      options = options || {}

      var table = this.quoteIdentifier(tableName)
      where = this.getWhereConditions(where)

      var query = "DELETE FROM " + table + " WHERE " + where

      return query
    },

    addIndexQuery: function(tableName, attributes, options) {
      var transformedAttributes = attributes.map(function(attribute) {
        if(typeof attribute === 'string') {
          return this.quoteIdentifier(attribute)
        } else {
          var result = ""

          if (!attribute.attribute) {
            throw new Error('The following index attribute has no attribute: ' + util.inspect(attribute))
          }

          result += this.quoteIdentifier(attribute.attribute)

          if (attribute.length) {
            result += '(' + attribute.length + ')'
          }

          if (attribute.order) {
            result += ' ' + attribute.order
          }

          return result
        }
      }.bind(this))

      var onlyAttributeNames = attributes.map(function(attribute) {
        return (typeof attribute === 'string') ? attribute : attribute.attribute
      }.bind(this))

      options = Utils._.extend({
        indicesType: null,
        indexName: Utils._.underscored(tableName + '_' + onlyAttributeNames.join('_')),
        parser: null
      }, options || {})

      return Utils._.compact([
        "CREATE", options.indicesType, "INDEX", options.indexName,
        (options.indexType ? ('USING ' + options.indexType) : undefined),
        "ON", tableName, '(' + transformedAttributes.join(', ') + ')',
        (options.parser ? "WITH PARSER " + options.parser : undefined)
      ]).join(' ')
    },

    showIndexQuery: function(tableName, options) {
      var sql = "SHOW INDEX FROM `<%= tableName %>`<%= options %>"
      return Utils._.template(sql)({
        tableName: tableName,
        options: (options || {}).database ? ' FROM `' + options.database + '`' : ''
      })
    },

    removeIndexQuery: function(tableName, indexNameOrAttributes) {
      var sql       = "DROP INDEX <%= indexName %> ON <%= tableName %>"
        , indexName = indexNameOrAttributes

      if (typeof indexName !== 'string') {
        indexName = Utils._.underscored(tableName + '_' + indexNameOrAttributes.join('_'))
      }

      return Utils._.template(sql)({ tableName: tableName, indexName: indexName })
    },

    attributesToSQL: function(attributes) {
      var result = {}

      for (var name in attributes) {
        var dataType = attributes[name]

        if (Utils.isHash(dataType)) {
          var template

          if (dataType.type.toString() === DataTypes.ENUM.toString()) {
            if (Array.isArray(dataType.values) && (dataType.values.length > 0)) {
              template = "ENUM(" + Utils._.map(dataType.values, function(value) {
                return this.escape(value)
              }.bind(this)).join(", ") + ")"
            } else {
              throw new Error('Values for ENUM haven\'t been defined.')
            }
          } else {
            template = dataType.type.toString();
          }

          if (dataType.hasOwnProperty('allowNull') && (!dataType.allowNull)) {
            template += " NOT NULL"
          }

          if (dataType.autoIncrement) {
            template += " auto_increment"
          }

          // Blobs/texts cannot have a defaultValue
          if (dataType.type !== "TEXT" && dataType.type._binary !== true && Utils.defaultValueSchemable(dataType.defaultValue)) {
            template += " DEFAULT " + this.escape(dataType.defaultValue)
          }

          if (dataType.unique === true) {
            template += " UNIQUE"
          }

          if (dataType.primaryKey) {
            template += " PRIMARY KEY"
          }

          if(dataType.references) {
            template += " REFERENCES " + this.quoteIdentifier(dataType.references)

            if(dataType.referencesKey) {
              template += " (" + this.quoteIdentifier(dataType.referencesKey) + ")"
            } else {
              template += " (" + this.quoteIdentifier('id') + ")"
            }

            if(dataType.onDelete) {
              template += " ON DELETE " + dataType.onDelete.toUpperCase()
            }

            if(dataType.onUpdate) {
              template += " ON UPDATE " + dataType.onUpdate.toUpperCase()
            }

          }

          if (dataType.comment && Utils._.isString(dataType.comment) && dataType.comment.length) {
            template += " COMMENT " + this.escape(dataType.comment)
          }

          result[name] = template
        } else {
          result[name] = dataType
        }
      }

      return result
    },

    findAutoIncrementField: function(factory) {
      var fields = []

      for (var name in factory.attributes) {
        if (factory.attributes.hasOwnProperty(name)) {
          var definition = factory.attributes[name]

          if (definition && (definition.indexOf('auto_increment') > -1)) {
            fields.push(name)
          }
        }
      }

      return fields
    },

    addLimitAndOffset: function(options, query){
      query = query || ""
      if (options.offset && !options.limit) {
        query += " LIMIT " + options.offset + ", " + 18440000000000000000;
      } else if (options.limit) {
        if (options.offset) {
          query += " LIMIT " + options.offset + ", " + options.limit
        } else {
          query += " LIMIT " + options.limit
        }
      }
      return query;
    },

    quoteIdentifier: function(identifier, force) {
      if (identifier === '*') return identifier
      return Utils.addTicks(identifier, "`")
    },

    quoteIdentifiers: function(identifiers, force) {
      return identifiers.split('.').map(function(v) { return this.quoteIdentifier(v, force) }.bind(this)).join('.')
    },

    quoteTable: function(table) {
      return this.quoteIdentifier(table)
    },

    /**
     * Generates an SQL query that returns all foreign keys of a table.
     *
     * @param  {String} tableName  The name of the table.
     * @param  {String} schemaName The name of the schema.
     * @return {String}            The generated sql query.
     */
    getForeignKeysQuery: function(tableName, schemaName) {
      return "SELECT CONSTRAINT_NAME as constraint_name FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE where TABLE_NAME = '" + tableName + "' AND CONSTRAINT_NAME!='PRIMARY' AND CONSTRAINT_SCHEMA='" + schemaName + "' AND REFERENCED_TABLE_NAME IS NOT NULL;"
    },

    /**
     * Generates an SQL query that removes a foreign key from a table.
     *
     * @param  {String} tableName  The name of the table.
     * @param  {String} foreignKey The name of the foreign key constraint.
     * @return {String}            The generated sql query.
     */
    dropForeignKeyQuery: function(tableName, foreignKey) {
      return 'ALTER TABLE ' + this.quoteIdentifier(tableName) + ' DROP FOREIGN KEY ' + this.quoteIdentifier(foreignKey) + ';'
    },

    mysqlDataTypeMapping: function(tableName, attr, dataType) {
      if (Utils._.includes(dataType, 'UUID')) {
        dataType = dataType.replace(/UUID/, 'CHAR(36) BINARY')
      }

      return dataType
    }
  }

  return Utils._.extend(Utils._.clone(require("../abstract/query-generator")), QueryGenerator)
})()